Bortnikov described fires across southern Europe as part of al-Qaida's "thousand cuts" strategy.

The director of the Federal Security Service on Wednesday blamed al-Qaida terrorists for starting forest fires in southern Europe, saying the tactic was designed to inflict widespread damage at little cost.

As evidence for his claim, Bortnikov cited instructions on how to wage "forest jihad" that his organization had spotted on extremist websites and forums.

Bortnikov, who described al-Qaida's incendiary tactics as part of a "thousand cuts" strategy, was referring to forest fires that have decimated vast swaths of crops and pristine woodland in countries from Spain to Greece this summer.

Spain's Agriculture Ministry said that more than 184,000 hectares was destroyed by fires between Jan. 1 and Sept. 16, the highest amount in a decade.

International environmental groups, including Greenpeace and the WWF, reacted to the FSB's comments with skepticism Wednesday, saying there was little evidence to support Bortnikov's remarks.

"There isn't the slightest doubt that the cause of the fires in the Mediterranean region was human error," said Nikolai Shmatkov, the WWF's forest policy director. "Ninety percent of fires happen through human negligence, either agricultural burning or carelessness."

Yevgenia Chirikova, an environmental-activist-turned-protest-leader who is running for mayor of the Moscow region city of Khimki, also dismissed the FSB's claims.

"Of course I don't believe them," she told Interfax. "And the tsunami in Japan, was that their work too?"